JPH0448368Y2 - - Google Patents

Description

[Detailed description of the invention] "Field of industrial application" This invention relates to an oil seal to be attached to a split housing on the crankshaft of an engine, and in particular to an improvement to improve the ease of assembly to the split housing. .

``Problems that cannot be solved by conventional techniques and ideas'' Conventionally, as shown in Fig. 3, the housing portion where the oil seal is mounted is divided into two parts, and half of the outer circumference of the oil seal is placed in one split housing 8 on the engine block side. , fit the other split housing 8' as a bearing cap onto the outer periphery of the remaining half, and tighten both housings 8, 8' with bolts 9 to install an oil seal. This structure is partially used in the rotating seal section of the crankshaft of an automobile engine.

By the way, the oil seal used in the conventional two-split housing is a peripheral rubber type in which a rubber seal layer 2' with a thickness of about 1.2 mm to 1.5 mm is baked on the outer periphery of an L-shaped reinforcing ring 1', as shown in Fig. 4. Since the seal layer 2' is formed to have an outer diameter that maintains the required fitting allowance, when half of the outer circumference of the oil seal is fitted into one split housing 8, as shown in FIG. Seal layer 2' on the mating surface of the housing
When the other split housing 8' is fitted in this state, the protruding rubber G is caught between the mating surfaces S of both housings, thereby creating a gap between the mating surfaces S. Also, when the oil seal is fitted to one of the split housings 8, the outer periphery near the mating surface is press-fitted into the housing, but
Since the other outer peripheral parts are in a slightly floating state, the oil seal uses the vicinity of the mating surface S as a fulcrum and wobbles back and forth, which causes problems such as tightening the oil seal at an angle. This was causing a leak.

Therefore, in the past, the process of assembling the oil seals required a high level of skill and skill, as well as using special jigs for assembly and retightening and adjusting if there was a problem, which required a great deal of work time and skill. is needed.

In particular, when a rubber with low compression fluidity (low plasticity) such as fluorine rubber is used in series with the lip as the sealing layer 2', the rubber G trapped in it becomes difficult to collapse even when the bolt is tightened. There were problems such as difficulty in assembly.

``Means for solving problems'' This invention aims to solve the above-mentioned conventional problems.
A rising part 3 bent and raised from the outer periphery of the lip attachment part 2, an outer periphery 4 which is reversely bent from its tip to the outer periphery, and a locking part 5 which is bent at right angles from the tip to the outer periphery are made of ultra-thin walls. A reinforcing ring 1 is integrally molded from a metal plate, and is approximately parallel to the inner circumferential surface of the two-split housing 8, 8' on the distal end side of the outer circumferential portion 4, and is crimped to the inner circumferential surface with the required fitting allowance. A crimping fitting part 4a is provided, and from this crimping fitting part 4a to the proximal end side, the two-split housing 8,
The loose fitting part 4 is tapered at a small angle so that the outer diameter gradually becomes smaller than the inner diameter of 8'.
b, and PTFE is applied to the outer peripheral surface of the crimp fitting part 4a.
An oil seal for a split housing is proposed in which an acrylic-PTFE sealant 7 containing 10 to 30% is applied and a rubber lip 6 is baked onto the inner peripheral edge of the lip attachment part 2.

"Function" When installing the oil seal configured as described above into the two-split housing, first fit half of the outer peripheral part 4 into one of the split housings 8, and then
By locking the oil seal to the end face of the split housing 8, the oil seal can be stably positioned and held at a regular position.

Next, the other housing 8' is fitted onto the remaining half of the outer circumference 4, and both housings 8, 8' are tightened with bolts 9.

At this time, the sealant 7 applied to the crimp fitting part 4a is bitten between the mating surfaces S of both housings 8, 8', but the maximum application thickness of the sealant 7 is approximately approx.
Since it is thin at about 40 μm, the amount of biting is naturally small, and sealant 7 has a PTFE content of 10 to 30%.
% blended acrylic-PTFE sealant with excellent compression fluidity, it is easily crushed by the tightening force of the bolt 9, leaving almost no gap between the mating surfaces S, and the housing 8 ' is also accurately tightened and fixed without causing any inclination, and oil leakage can be reliably prevented.

Furthermore, since the reinforcing ring 1 is made of an extremely thin metal plate and is easily deformed elastically, when the housings 8, 8' into which the reinforcing ring 1 is inserted are tightened with the bolts 9,
The force required to clamp the fitting margin of the crimp fitting portion 4a of the reinforcing ring 1 is reduced, and the remaining force is used to crush the sealant 7 between the mating surfaces S of the housings 8, 8. The sealant 7 can be crushed more strongly, and as a result, the gap between the mating surfaces S can be reduced.

It is important to reduce the gap between the mating surfaces S of the two-split housings 8, 8' in order to reduce oil leakage at the mating surfaces S.

That is, when the engine is running, the two-split housings 8 and 8' are heated and expand thermally, so the gap between their mating surfaces S becomes smaller, but when the engine is stopped, they cool and contract, so the gap between the mating surfaces S becomes smaller. On the other hand, if the gap between the housings 8 and 8' is large when they are fastened, the difference in the gap between heating and cooling will be correspondingly large. Due to the shrinkage of the gap between the mating surfaces S, the sealant is greatly crushed and plastically deformed, and when the gap between the mating surfaces S expands greatly during subsequent cooling, the gap between the mating surfaces S and the sealant cannot be followed, and the gap between the mating surfaces S and the sealant increases. This results in oil leakage.

Figure 6 shows test pieces (3 mm in length and width and 7 μm in thickness) of sealants of various qualities used in the oil seal of the present invention and fluorocarbon rubber used in conventional outer peripheral rubber type oil seals, divided into two housings 8 and 8.
8' and bolted, and examined the relationship between the surface pressure of the mating surface S and the film thickness of the test piece.As is clear from the results, the above acrylic-PTFE system It can be seen that the sealant collapses thinly even if the tightening force of the bolt 9 is small, and the gap between the mating surfaces of the housing can be made much smaller with a small tightening force compared to the rubber used for the seal layer of conventional oil seals. .

In this test, test pieces with the same dimensions were used in order to perform a comparative test under the same conditions, but when the oil seal of this invention and the conventional oil seal with outer periphery rubber were actually tightened, the amount of sealant protruding from the seal was Since the amount of protrusion of the rubber layer is much smaller than that of the rubber layer, the oil seal according to the present invention actually creates almost no gap between the mating surfaces with a smaller tightening force than the above test results compared to the conventional oil seal. It can be tightened without any problem.

Furthermore, since a loose fitting part 4b is provided which is tapered at a small angle so that the outer diameter gradually becomes smaller than the inner diameter of the housing 8, 8' from the crimp fitting part 4a to the proximal end side, When a new oil seal of the present invention, which is a replacement part, is hammered into the housing 8, 8' which is still in the fastened state during part replacement during overhaul, etc., the oil seal can be inserted into the housing extremely smoothly and reliably without deforming the oil seal. It can be fitted.

``Example'' Below, we will explain an example of this invention shown in the drawings.The reinforcing ring 1 is formed from an extremely thin metal plate with a wall thickness of 1/2 to 1/3 of that of a metal plate used for a normal oil seal. A rising part 3 is provided that is bent upward from the outer periphery of the lip attachment part 2, and an outer periphery 4 is provided that is inverted and bent from the tip of the rising part 3 toward the outer periphery. A series of locking portions 5 bent at right angles are provided.

A seal lip 6 made of heat-resistant rubber such as fluorine rubber is baked onto the inner peripheral edge of the lip attachment part 2, and an acrylic seal lip 6 is baked onto the outer peripheral surface of the outer peripheral part 4.
A sealant 7 made of a PTFE sealant (containing 10 to 30% PTFE) and having good compression fluidity is applied.

A crimp fitting part 4a is provided on the distal end side of the outer peripheral part 4 of the reinforcing ring 1, which is approximately parallel to the inner peripheral surface of the housing 8, 8' with a required fitting margin and is crimped and fitted to the inner peripheral surface of the housing 8, 8'.
and further tapered at a small angle (contact angle with the housing of about 18° or less) so that the outer diameter gradually becomes smaller than the inner diameter of the housing 8, 8' from the crimp fitting part 4a to the proximal end side. A loose fitting portion 4b is provided, and a sealant 7 is applied to the crimp fitting portion 4a.

The entire crimp fitting portion 4a or at least the loose fitting portion 4
If the fitting allowance near b is tapered at a minute angle so that the diameter gradually decreases by a minute amount toward the loose fitting part 4b, in addition to the taper of the loose fitting part 4b, the oil seal housings 8, 8 ′ becomes even better in hammering.

The reinforcing ring 1 is preferably formed from a thin cold-rolled steel plate (SPCC) and then subjected to hardening treatment such as nitriding treatment so as to maintain sufficient residual fitting allowance after fitting into the housing. .

``Effect of the invention'' As described above, according to this invention, the outer peripheral surface of the reinforcing ring is made of acrylic resin containing 10 to 30% PTFE.
By applying a PTFE sealant with excellent compressive fluidity, even when attached to a split housing and tightened with bolts, the thickness of the sealant coating is extremely thin.
The amount of sealant caught between the mating surfaces of both housings is extremely small, and since the sealant has compressive fluidity and is easily crushed into a thin layer, the gap between the mating surfaces when the housing is tightened is extremely small. In addition to reliably preventing oil leakage, since the locking portion is provided at the tip of the outer peripheral portion and is bent at right angles to the outside, it is possible to reliably prevent the oil seal from being installed at an angle to the housing.

In addition, since the reinforcing ring is made of an extremely thin metal plate and is easily deformed elastically, when the two-split housing into which the reinforcing ring is inserted is tightened with bolts, the fitting margin of the crimp fitting part of the reinforcing ring is compressed. Less tightening force is required, and the excess force is used to crush the sealant that has protruded between the mating surfaces of the housing, making it possible to crush this sealant more forcefully, and as a result, the gap between the mating surfaces of the housing can be closed. By reducing the amount, oil leakage can be reliably prevented.

Further, the outer circumference of the reinforcing ring is provided with a loose fitting part that is tapered at a small angle so that the outer diameter gradually becomes smaller than the inner diameter of the housing from the crimp fitting part to the proximal end side. Therefore, by applying a sealant to the crimp fitting part, it is possible to prevent the oil seal from deforming when the new oil seal of the present invention, which is a replacement part during overhaul or maintenance, is hammered into the housing that is still in the fastened state. It can be fitted into the housing extremely smoothly and reliably without any problems.

In addition, in conventional outer peripheral rubber type oil seals, in order to reduce the gap caused by the rubber of the seal layer being caught, it is necessary to use rubber with high compression fluidity (high plasticity) even in the lip that is integrated with the seal layer. However, since the oil seal of this invention does not require a sealing layer, a rubber material such as fluorine rubber with low compression fluidity (low plasticity) can be used for the seal lip without selecting a rubber material.

[Brief explanation of the drawing]

Fig. 1 is a partial vertical sectional view of the oil seal of this invention, and Fig. 2 is a longitudinal sectional side view showing the oil seal of this invention assembled in a two-split housing.
Fig. 3 is a front view of the same, Fig. 4 is a partial longitudinal sectional view showing a conventional oil seal, Fig. 5 is a partial longitudinal sectional front view showing a state in which the conventional oil seal is assembled into a two-split housing, and Fig. 6 is a partial vertical sectional view of the conventional oil seal. FIG. 3 is a diagram showing the relationship between the surface pressure of the mating surfaces and the film thickness of the test piece when a bolt tightening test of the split housing is performed using various test pieces. DESCRIPTION OF SYMBOLS 1...Reinforcement ring, 2...Rip attachment part, 3...Rise part, 4...Outer peripheral part, 4a...Crimp fitting part, 4b
... Loose fitting part, 5 ... Locking part, 6 ... Seal lip, 7 ... Sealant, 8, 8' ... Housing,
9...Bolt, 10...Crankshaft, S...Mating surface.

Claims (1)

[Scope of utility model registration request] An ultra-thin metal plate is used to connect the rising part bent from the outer periphery of the lip attachment part, the outer periphery bent inverted from its tip to the outer periphery, and the locking part bent at right angles from the tip to the outer periphery. An integrally molded reinforcing ring is provided, and a crimping fitting portion is provided on the tip side of the outer peripheral portion, which is substantially parallel to the inner peripheral surface of the split housing and is crimped to the inner peripheral surface with a required fitting margin. , a loose fitting part is formed in a tapered shape at a small angle so that the outer diameter gradually becomes smaller than the inner diameter of the two-split housing at the time of fastening from the crimp fitting part to the proximal end side, and the crimp fitting part on the outer peripheral surface of
An oil seal for a split housing, characterized in that an acrylic-PTFE sealant containing 10 to 30% PTFE is applied, and a rubber lip is baked onto the inner peripheral edge of the lip attachment part.